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AFRICA
CVJAFRICA • Volume 26, No 2, H3Africa Supplement, March/April 2015
at the Lagos University Teaching Hospital, Lagos, south-west
Nigeria. The study protocol was approved by the health research
and ethics committee of the hospital and each participating
individual gave written informed consent.
Recruitment into the FDR arm of the study was carried out
in two phases. In the first phase of recruitment, we enrolled 106
probands who were consecutively presenting and consenting
patients with CKD attending the nephrology out-patient clinic
of our teaching hospital. To be eligible for recruitment in this
phase, a patient had to be 18 years of age or older and give
informed consent. Patients with CKD from autosomal dominant
polycystic kidney disease (ADPKD) were excluded. In the second
phase, we recruited FDRs of the 106 probands with CKD.
A minimum of one and a maximum of four FDRs were
selected from the family of each proband. Where there were four
or less eligible FDRs in the family of a proband, all of them
were recruited into the study. However, where there were more
than four eligible FDRs in the family of a proband, four were
selected by balloting.
Individuals were eligible for recruitment into the FDR arm
of the study if they were: a parent, sibling or offspring of
one of the probands, were 18 years of age or older, and gave
informed consent. Exclusion criteria included: age less than 18
years, presence of symptomatic urinary tract infection, on-going
febrile illness, presence of heart failure, severe current illness or
malignancy, and a family history of ADPKD.
For the control arm of the study, individuals who were age
and gender matched with subjects in the FDR arm, and had
no family or personal history of CKD were enrolled. Inclusion
criteria for subjects in the control arm were: age 18 years or
older, absence of personal or family history of CKD and giving
informed consent. The exclusion criteria were: age less than 18
years, presence of symptomatic urinary tract infection, on-going
febrile illness, heart failure, or other severe current illness or
malignancy.
Information was retrieved from the study participants using an
interviewer-administered structured questionnaire. Information
obtained included: socio-demographic data, personal and family
history of kidney disease, a history of diabetes and hypertension,
current or past use of medications including herbal preparations
and over-the-counter drugs. Information regarding social habits
such as cigarette smoking and alcohol consumption were also
retrieved.
The weight, height, waist and hip circumferences, and blood
pressure were measured in each study participant. Ten millilitres
each of early morning spot urine and venous blood were
obtained from all participants following an overnight fast
for the determination of levels of serum creatinine, fasting
plasma glucose, fasting lipids and serum uric acid, and urine
albumin:creatinine ratio. Glomerular filtration rate was estimated
from serum creatinine using a four-variable version of the
modification of diet in renal disease (MDRD) study equation.
19
Diabetes mellitus was defined as a fasting plasma glucose
level
>
126 mg/dl (7 mmol/l), or diabetes mellitus diagnosed
previously by a physician, or use of insulin or oral hypoglycaemic
medications.
20
Hypertension was defined as systolic BP
≥
140
mmHg or diastolic BP
≥
90 mmHg, hypertension previously
diagnosed by a physician, or use of antihypertensivemedications.
21
Overweight was defined as body mass index (BMI) 25–29.5 kg/
m
2
and obesity was defined as BMI
≥
30kg/m
2
.
22
Truncal obesity
was defined as waist circumference
≥
102 cm in males and
≥
88
cm in females.
23
Hyperuricaemia was defined as a serum uric
acid level of
≥
7 mg/dl.
24
Dyslipidaemia was defined as a ratio of
plasma total cholesterol and high-density lipoprotein cholesterol
(TC/HDL-C)
>
5.
25
Moderate alcohol drinking was defined as consumption of
one drink (14 g) per day.
26
Moderate-to-heavy cigarette smoking
was defined as smoking at least six cigarettes per day.
27
Statistical analysis
Statistical analyses were carried out using the statistical
package for social sciences (SPSS), version 17.0 (SPSS Inc,
Chicago, IL). Continuous data are presented as mean
±
SD and
categorical variables are expressed as proportions or percentages.
Independent samples
t
-tests were used for comparison of
group means, while the chi-square test (
χ
2
tests) was applied
for comparison of categorical variables in FDRs and controls.
Multiple logistic regression analysis was used to determine CVD
risk factors that were independently associated with being a
FDR of a patient with CKD. Significance was set at a
p
-value
less than 0.05.
Results
The 230 FDRs comprised 25 parents (10.8%), 78 siblings (34%)
and 127 offspring (55.2%). The parents were seven fathers (3.0%)
and 18 mothers (7.8%), the siblings were 39 brothers (17%) and
39 sisters (17%), while the offspring were 69 sons (30.0%) and
58 daughters (25.2%). Age- and gender-matched 230 healthy
adults were recruited into the control arm of the study. Table 1
shows the clinical and biochemical characteristics of the FDRs
and controls. FDRs of the patients with CKD had significantly
higher mean systolic blood pressure, mean diastolic blood
pressure, mean body mass index, mean waist circumference and
urine albumin:creatinine ratio than the controls.
Table 2 shows a comparison of the prevalence of risk
factors for CVD between the FDRs of patients with CKD and
the control group. The prevalence of hypertension, diabetes,
obesity, dyslipidaemia, hyperuricaemia, albuminuria and
reduced estimated glomerular filtration rate (eGFR) were all
significantly higher among the FDRs than in the control
subjects. Hypertension (OR, 1.65), dyslipidaemia (OR, 1.72)
and albuminuria (OR, 1.61) are CVD risk factors that were
independently associated with being a FDR of a patient with
CKD (Table 3).
Discussion
Our study showed that among our sub-Saharan African cohort,
as was previously reported in other populations, risk factors
for cardiovascular disease were more prevalent in the FDRs of
patients with CKD compared to healthy control subjects. This
finding supports the phenomenon of a clustering of CVD risk
factors in families of patients with CKD.
Hypertension and diabetes are two of the most important
CVD risk factors worldwide. In this study, the prevalence of both
conditions was significantly higher among FDRs of patients
with CKD than in the control group. However, the picture was
slightly different when the prevalence was compared with the